A coolant passage of a vehicular cooling system includes a battery coolant passage through which a coolant is supplied from a radiator to a battery, a discharge coolant passage through which the coolant is supplied to the radiator, a first bypass passage through which the coolant is supplied from the discharge coolant passage to the battery coolant passage while bypassing the radiator, and a switching valve that switches a pathway of the coolant, between a first pathway through which the coolant is supplied from the discharge coolant passage to the battery coolant passage via the radiator and a second pathway through which the coolant is supplied from the discharge coolant passage to the battery coolant passage via the first bypass passage. An electronic control unit controls the switching valve such that the pathway is switched to the second pathway at the time of increasing a temperature of the battery.